I have in my posession two seeming oddities.

The first is a brake master cylinder, with no identifying casting numbers or stampings on it. However, it resembles the standard Ford/ Bendix master cylinder that you would find in a 1970's F-series truck. The only oddity is that it measures 3" X 6" at the cap, which makes it longer than your average master cylinder. However, it has the standard 1" bore.
I've been sourcing replacement parts for this cylinder but have come up against a brick wall. The standard 1968-1972 F100 master cylinder cap measures 3 1/8" at the cap, sure, but is it 6"? The secondary and primary piston seals is easy enough to replace, but the cap. Anyone have any idea if a 1968-1972 cap would fit?

The second item is a master cylinder that resembles a 1961-1966 F100 version, with the exception that the bore is 1 1/8" and it is clearly marked as a Wagner-Lockheed item. The bore is in good nick and the piston is primo. Finding a repair kit was a breeze. But the cap is in poor condition, which measures 2 5/8" at the cap. Would a 1961-1966 F100 replacement screw-on cap fit?

 

Pictures will help especially with something this old.